Paying Fishers to Release Endangered Marine Species: A Double-Edged Sword for Conservation
A groundbreaking study led by researchers at the University of Oxford has unveiled the complex dynamics of incentivizing small-scale fishers to release endangered bycatch species alive. Conducted over 16 months in Indonesian waters, this research represents the first randomized controlled trial rigorously evaluating the efficacy of a compensation-based marine conservation strategy. Published in Science Advances on April 23, 2025, the findings highlight that while financial incentives can significantly increase live releases of critically endangered species, they also risk provoking unintended behaviors that potentially undermine conservation goals.
Endangered marine fauna, particularly species like hammerhead sharks (Sphyrna) and wedgefish (Rhynchobatus), are under dire threat globally. Their susceptibility to overfishing, both as targeted catches and incidental bycatch, places serious pressure on global biodiversity. The challenge intensifies in small-scale fisheries where fishing is not merely an economic activity but a source of subsistence and food security for coastal communities. Thus, any intervention must delicately balance conservation objectives with local livelihoods.
The incentive program evaluated here was a collaboration between Oxford researchers and the Indonesian non-governmental organization Kebersamaan Untuk Lautan (KUL). The pay-to-release scheme involved compensatory payments to fishers who could provide verifiable proof of safely releasing captured hammerhead sharks and wedgefish. Verification required video evidence, recorded on cameras supplied to fishers, that showed the released animal swimming away unharmed and out of sight. This methodological rigor in verifying compliance sets this program apart from many previous conservation initiatives.
Eighty-seven fishing vessels operating in local Indonesian fisheries were randomly divided into treatment and control groups. Treatment vessels were eligible for financial compensation based on prior economic assessments of the potential income foregone from selling the threatened species in local markets. This valuation ensured that payments aligned closely with the opportunity cost to fishers, aiming to create a compelling and fair incentive.
Results were striking yet nuanced. The program dramatically increased live releases of wedgefish, with 71% of caught wedgefish being released alive by incentivized fishers. Hammerhead shark live release rates improved more modestly, with 4% of these individuals released in the treatment group versus near-zero in controls. Despite these positive signals, closer analysis revealed that some fishers in the treatment group altered their behavior counterproductively. Certain vessels increased their catch rates of the incentivized species, presumably aiming to maximize compensation. This “perverse incentive” effect ultimately reduced the net conservation benefit.
Specifically, when considering total mortality—including that arising from the increased catch rates—wedgefish mortality was only 25% lower in the treatment group relative to controls. More alarmingly, hammerhead shark mortality rose by 44%. These findings underscore the profound complexity inherent in designing incentive schemes in real-world socio-ecological systems, where economic rationality and conservation goals may conflict.
In response to these outcomes, KUL adapted their program design. They instituted a size-based compensation scale, capping compensable releases per vessel weekly and piloted gear-switching initiatives to preempt catches of endangered species altogether. Early indications suggest that these refinements mitigate the unintended incentives and may enhance program effectiveness. The continuous randomized control trial structure and Oxford’s ongoing collaboration help generate iterative learning to optimize conservation impact.
From a conservation science perspective, this study underscores the imperative of rigorous experimental evaluation of incentive-based conservation policies. Pay-to-release programs, though increasingly popular worldwide, often lack hard evidence validating their effect on biodiversity or socio-economic outcomes. This research compellingly demonstrates that without precise calibration and empirical validation, such interventions risk wasteful expenditures and unintended ecological harm.
Lead Oxford biologist Dr. Hollie Booth emphasized the ethical dimensions of conservation incentives. She noted that small-scale fishers should not bear disproportionate conservation costs borne primarily to remedy damages inflicted by more powerful interests. Nonetheless, incentive programs must be carefully structured and empirically validated to foster trust, fairness, and genuine ecological benefit.
Senior researcher Professor Paul Ferraro from Johns Hopkins University, a leading expert in behavioral economics and conservation, articulated concerns about the widespread adoption of pay-to-release programs without robust impact evaluation. His reflection spotlights a broader issue in global conservation financing: the frequent lack of rigorous, data-driven accountability measures.
Local fisheries authorities echoed the program’s nuanced impact. Teuku Ridwan, head of the Department of Marine Affairs and Fisheries for Aceh Jaya Regency, highlighted tangible benefits to livelihoods and underscored the value of sustained collaborations between fishers, NGOs, traditional leaders, and government actors. These social synergies are critical to achieving marine management paradigms that are both sustainable and culturally grounded.
This research also speaks to the global biodiversity agenda, linking local-level intervention to the United Nations’ Global Biodiversity Framework’s 2050 vision of “living in harmony with nature.” The urgent need to bend the curve of biodiversity loss requires not only innovative conservation tools but also adaptive management informed by rigorous scientific evidence.
Beyond conservation implications, this study exemplifies the importance of interdisciplinary approaches that integrate biological sciences, economics, and social dynamics. The nuanced behavioral responses of fishers illustrate how human incentives can interact with ecological systems in complex ways, demanding sophisticated program design and continuous evaluation.
The researchers note that their experimental design, including video verification and randomized allocation of incentives, provides a template for future interventions seeking to align economic incentives with conservation outcomes. As marine ecosystems face escalating threats, integrating rigorous experimentation with adaptive governance promises to enhance the effectiveness, transparency, and equity of conservation programs globally.
In summary, the Oxford-led randomized controlled trial offers both hope and caution regarding pay-to-release schemes. On one hand, monetary incentives can tangibly increase the survival of critically endangered marine species. On the other hand, without careful calibration, these same incentives may inadvertently escalate pressures on vulnerable populations. This duality compels conservation scientists and practitioners alike to embrace robust experimental evaluation and iterative redesign for truly impactful marine biodiversity conservation.
Subject of Research: Marine conservation through incentive-based pay-to-release programs targeting endangered sharks and rays in small-scale fisheries.
Article Title: Conservation impacts and hidden actions in a randomized trial of a marine pay-to-release program
News Publication Date: 23 April 2025
Web References:
References:
- Booth, H., et al. (2025). Conservation impacts and hidden actions in a randomized trial of a marine pay-to-release program. Science Advances. DOI: 10.1126/sciadv.adr1000
- Prior Oxford team work on valuation of catches: ScienceDirect Article
Image Credits: Francesca Page, Liam Webb
Keywords: marine conservation, pay-to-release, endangered species, wedgefish, hammerhead sharks, bycatch, behavioral incentives, randomized controlled trial, small-scale fisheries, Indonesia, biodiversity loss, conservation evaluation
